The invention concerns a method and a device for cooling a motor vehicle engine.
The invention concerns, more particularly, a device comprising a hydraulic circuit of cooling fluid, associated with a pump for circulating it through the engine of the vehicle and different branches of the circuit. Thermal equipment of the vehicle can be arranged in the different branches of the circuit.
Cooling systems are designed in order to ensure the resistance of the engine to the thermomechanical stresses resulting from combustion. In addition, complementary functions are implemented beyond the main cooling of the engine, in order to improve the overall efficiency or to provide and guarantee benefits to vehicle users, such as, for example, the heating of the passenger compartment.
The cooling systems are dimensioned using only operation points at maximum speed and full load of the engine, and are thus overdimensioned in the majority of usage cases of the vehicles.
Thus, the operation parameters of the engine are not optimized, which leads to a degradation of its performances, such as an increased consumption, a high level of emission of pollutants as well as a reduction in the heating and acoustic comfort of the vehicle.
One purpose of the present invention is to propose a method for cooling a motor vehicle engine, correcting all or a part of the disadvantages of the prior art mentioned above.
This purpose is achieved by the fact that the method for cooling a motor vehicle engine consists in regulating the volume and the flow rate of a cooling fluid in a hydraulic circuit provided with a degassing branch in which is arranged a degassing box, and comprises a step of determining the temperature of the cooling liquid, a step of comparing the temperature of the cooling liquid with a first threshold temperature, and a step of regulating the circulation of fluid in the degassing branch such that, when the temperature of the fluid is higher than the first threshold temperature, the quantity of fluid circulating in the branch is greater than the quantity of fluid circulating in that same branch when the temperature of the fluid is lower than the first threshold temperature.
According to another characteristic, the method comprises a step of comparing the temperature of the cooling fluid with a second threshold temperature, in a manner such that when the temperature of the fluid is higher than the second threshold temperature, the quantity of fluid allowed to circulate in the branch is greater than the quantity of fluid allowed to circulate in that same branch when the temperature of the fluid is lower than the second threshold temperature.
Another purpose of the present invention is to propose a device for cooling a motor vehicle engine, correcting all or a part of the disadvantages of the prior art mentioned above.
This purpose is achieved by the fact that the device for cooling a motor vehicle engine, of the type comprising a hydraulic circuit of a cooling fluid, associated with a pump for circulating the fluid through the engine of the vehicle and different branches of the circuit, in which are arranged thermal equipment of the vehicle, at least some of the branches being equipped with electronically controlled actuators to regulate the circulation of the fluid in these branches, the device comprising means for collecting information relating to the operation conditions of the vehicle, connected to means for controlling the operation of the actuators, in order to control the volume and the flow rate of fluid circulating in the hydraulic circuit so as to optimize the operation of the engine, the circuit comprising a degassing branch equipped with an electronically controlled actuator and in which a degassing box is arranged, the information collection means being adapted to determine the temperature of the cooling fluid so that the control means regulate the circulation of the fluid in the degassing branch such that, when the temperature of the fluid is higher than a first threshold temperature, the quantity of fluid circulating in the branch is greater than the quantity of fluid circulating in that same branch when the temperature of the fluid is lower than the first threshold temperature.
In addition, the invention may comprise one or more of the following characteristics:
the control means regulate the circulation of fluid in the degassing branch in a manner such that, when the temperature of the fluid is higher than a second threshold temperature, the quantity of fluid circulating in the branch is greater than the quantity of fluid circulating in this same branch when the temperature of the fluid is lower than the second threshold temperature,
when the temperature of the fluid is between the first and the second threshold temperatures, the control means regulate the circulation of the fluid in the branch (6) as a function of the temperature of the cooling liquid, in a manner such that the quantity of the liquid circulating in the branch increases when the temperature of the liquid increases,
the actuator of the degassing branch is of the xe2x80x9call or nothingxe2x80x9d type, the control means cooperating with the collection means, in order to control the opening of the actuator when the temperature of the fluid is higher than the second threshold temperature,
the second threshold temperature is between 60 and 100 degrees approximately,
the first threshold temperature is between 20 and 60 degrees approximately and defines the temperature of the fluid below which the state of the engine is referred to as xe2x80x9ccoldxe2x80x9d,
the control means cooperate with the collection means, in order to calculate, on the one hand, the average instantaneous power supplied by the engine and then, on the other hand, the first threshold temperature as a function of the average instantaneous power and a specified modeling of the operation of the engine which defines its cold state (first threshold temperature) as a function of average power,
when the temperature of the cooling liquid is lower than the first threshold temperature, the control means control the opening of the actuator and the quantity of fluid circulating in the degassing branch as a function of the average power supplied by the engine, the quantity of liquid allowed to circulate in the branch increasing when the average power (Pm) supplied by the engine increases,
the actuator of the degassing branch is of the xe2x80x9call or nothingxe2x80x9d type, the control means controlling the opening of the actuator according to a square pulse signal varying as a function of the average power supplied by the engine,
the actuator of the degassing branch is of the total opening and closing type, the control means control the opening of the actuator according to a square pulse signal varying as a function of the average power supplied by the engine,
the control means controlling the opening of the actuator according to a square pulse signal so that the quantity of liquid circulating in the branch increases linearly with the temperature of the cooling liquid.
the opening time of the valve is constant, the period of the signal being inversely proportional to the temperature of the cooling liquid.